Newspaper reports say Major League Baseball slugger Jason Giambi told a federal grand jury that he took steroids and other performance-enhancing substances. The disclosure extends a widening scandal and probe involving a San Francisco based company and previously undetectable drugs.

The San Francisco Chronicle reported Thursday that the New York Yankees star said he began using steroids in 2001. The 33-year-old Giambi has in public denied using performance-enhancing drugs. But the newspaper says he testified during a closed hearing in December 2003 that he used steroids supplied by the drug firm BALCO. That year, Giambi slammed 41 home runs for the World Series runner-up Yankees.

The report is based on a transcript of the baseball star's testimony in the BALCO steroids case that has led to charges against four men. Such testimony is typically sealed. But leaks to local newspapers have been common throughout the case.

Major League Baseball had no formal testing program for steroids until this season. League commissioner Bud Selig said he wants to expand the program to match a plan he previously devised. "I instituted a very, very tough program in the Minor Leagues on steroids in 2001. We need to have that same program at the Major League level," he said.

Before the testimony of Giambi, former stars Jose Canseco and Ken Caminiti were the only Major League Baseball players to admit they had used performance-enhancing steroids. Baseball commissioner Selig did not comment about Giambi specifically, but said the news of his alleged drug use is another call for action. "This is just another manifestation of why we need that [program] right away. So I would tell you today, my only reaction is we are going to leave no stone unturned until we have that policy in place by Spring training of next year," he said.

Banned drugs known as THG were first detected a year ago and were allegedly supplied by BALCO. The discovery touched off a scandal which has focused primarily on track and field athletes. Baseball trainer Greg Anderson, BALCO executives Victor Conte [kahn-tee] and James Valente and athletics coach Remy Korchemny face steroid distribution charges in the BALCO case. All have pleaded not guilty.